Verdict: On the one hand, this is extremely expensive, and can only be used if you already have a late-game trap. On the other hand, this is the strongest trap in the game by far. ULTIMATE POWER- *cough*

The General Store sells a Repurposed Robot Head for 100,000 gold, which is necessary for the event "quest". It also sells several crafting materials intended for the late-game Living Garden areas, to create souped-up charms to speed up progress in the minigames there. They are a bit on the pricey side.

Similarly, the Charm Shoppe contains various "luxury" charms.

The Party Charm changes the mice you can get from Ronza's Travelling Shoppe, but is rather expensive; besides, you can get them as free gifts from friends anyway. (to send them, go to Friends → Send Free Gifts).

Mining Charms are useful if you are planning to hunt for Big Bad Burroughs mice in the Town of Digby using Limelight cheese. See the Town of Digby Revisited chapter for details.

Tarnished Charms aren't very useful in their current state, but they turn into Chrome Charms, a staple for those who participate in tournaments and when the extra edge might be useful. You don't want to be using them all the time though.

Safeguard Charms decrease the rate of encountering Cursed and Corrupt mice in the Lost City and Cursed City locations.

Grubling Bonanza Charms immediately trigger a Grubling Stampede if used in the Sand Dunes location.

If you wish to try raising money for the traps, check out the Gold and Super Brie appendix for details.

Otherwise, it's time to hunt in the Travelling Shoppe to fight the Force Fighter mice! There are five of them, each having a different color. They drop a robot part corresponding to their color, and a lot of action figures (collectibles). As the description notes, apparently they are so poorly made, no one would buy them...

The head, as mentioned, would need to be bought in the General Store for 100,000 gold.

Once you have all the parts, you may redeem the Ultra MegaMouser MechaBot Trap from the trapsmith.

Bases from past birthday celebrations, dropped by various mice in the Travelling Shoppe. These include the Birthday Cake Base, the Chocolate Birthday Cake Base, the Carrot Birthday Cake Base, and the Cheesecake Base. The Cheesecake Base in particular has the same attraction bonus as the Wooden Base With Target, but has better stats. It is thus useful in the limited situations where attraction bonus is more important than power.

Rockforth cheese, dropped by the mice here, and used to attract the elusive Rockstar mouse.

Fifth Birthday Gifths, dropped by Birthday Mice. Open them to receive some King's Credits (usable in the King's Arms shoppes) and supplies. You may even get some Super Brie.